GPU-Z is one of our favorite tell-all utilities to carry around on a USB stick. It doesn't require any installation, it has a small footprint (around 900KB), and it reveals just about everything you could want to know about your videocard, from the BIOS version to the number of ROPs. TechPowerUp is pretty good about keeping GPU-Z updated, and the latest build adds support for AMD's Radeon HD 7970 and 7350 graphics, as well as a few other enhancements.
GPU-Z v0.5.7 fleshes out support for a few other GPUs, including AMD's Radeon E6760, HD 3650, HD 5570, HD 6450A, HD 6470M, and FirePro V4800 and V3800.
In addition to better support for the above GPUs, the update fixes half a dozen issues, including one where PCi-E 3.0 might show up as PCI-E 2.0.